1. Field of the Invention
An aspect of the invention relates to a method of measuring a degree of crystallinity of a polycrystalline silicon substrate, a method of fabricating an organic light emitting display using the same, and an organic light emitting display fabricated using the same, and, more particularly, to a method of measuring a degree of crystallinity of a polycrystalline silicon substrate using a Raman spectrum graph, a method of fabricating an organic light emitting display using the same, and an organic light emitting display fabricated using the same.
2. Description of the Related Art
Since polycrystalline silicon has a high mobility compared to amorphous silicon (a-Si for short), polycrystalline silicon is used in various electronic devices such as solar cells and flat panel displays.
The mobility of polycrystalline silicon is related to a degree of crystallinity of the polycrystalline silicon. Methods of estimating the degree of crystallinity may include a Raman spectroscopic analysis method.
When a transparent material is irradiated with an intense monochromatic light and the spectrum of light scattered from the transparent material is analyzed, spectral lines having a longer or shorter wavelength than the wavelength of the incident light are observed in addition to a spectral line having the wavelength of the incident light. This phenomenon is known as the Raman effect. A Raman spectroscopic analysis method uses the Raman effect.
In general, the degree of crystallinity of the polycrystalline silicon is estimated based on a full width at half maximum (FWHM) of a Raman spectrum graph. Specifically, as the FWHM of the Raman spectrum graph decreases, the degree of crystallinity of the polycrystalline silicon increases.
However, the method of measuring the degree of crystallinity based on the FWHM of the Raman spectrum graph has a problem in that the method tends to be unreliable.
In addition, the aforementioned method of measuring the degree of crystallinity has a problem in that the method does not consider the dispersion of a threshold voltage (Vth) that is an important characteristic of a thin film transistor.